1. Field of the Invention
The present invention relates to a battery-powered handheld vacuum for use at building sites, which has a dust collection box and a motor housing; situated inside the motor housing are a drive motor equipped with a fan impeller and a battery pack to supply current to the drive motor independently of an electrical network, the dust collection box being mounted on the motor housing so as to be detachable.
2. Description of Related Art
A battery-powered handheld vacuum device of this type is known from published European patent application document EP 1 523 916 A2; it includes a dust collection box that is mounted on a motor housing in detachable manner; situated inside the motor housing are a drive motor equipped with a fan impeller and a battery pack for supplying current to the drive motor independently of an electrical network. A cup-shaped main filter is disposed inside the dust collection box; it is enclosed by a pre-filter, which is likewise developed in the shape of a cup and situated in the dust collection box coaxially to the main filter. The pre-filter and the main filter share a common axis of rotation, which extends coaxially to an axis of rotation of the fan impeller and the drive motor accommodated in the motor housing, the impeller fan having an outer diameter that is greater than an outer diameter assigned to the main filter, but smaller than an outer diameter assigned to the pre-filter.
The disadvantage of the related art is that the length of this battery-operated handheld vacuum device is relatively long due to the coaxial placement of the cup-shaped filters, fan impeller and drive motor. Moreover, because of the cup-shaped design of the filters and the thereby specified conditions of the outer diameters of the filters in relation to the fan impeller, this battery-operated handheld vacuum device has a relatively large cross-section in the longitudinal direction.